Valves have been used for many centuries in a variety of applications. As the technology has progressed, more sophisticated uses have been found for valves. For instance, various improvements have been made in methods of actuation of the valve. Some of these methods include motor driven actuation, solenoid actuation and more recently, computer controlled actuation, and so forth. However, the essential flow design of valves has stayed relatively constant along four basic designs.
One type of valve used is a gate valve. It is simple in design, inexpensive, and can be used in a variety of applications. A gate valve typically contains a circular disk, known as a gate, mounted transverse to a conduit or pipe which engages a seat to block or restrict flow. A gate valve is generally known to those in the art as being poor for controlling flow other than in a fully-opened or fully-closed position. The interface between the gate and its seat generally erodes and is prone to maintenance.
Another typical valve is known as a globe valve. Those in the art know that it is good for throttling at other than fully-opened or fully-closed positions. An example is shown in U.S. Pat. No. 4,066,090 to Nakajima et al. As can be seen, the flow path is somewhat circuitous resulting in generally higher friction losses, nonlaminar flow, and may prematurely induce flow separation and/or cavitation. Thus, flow rates tend to be less than those of a fully-opened gate valve, the fluid flow path tends to wear, and the globe valve, because of its inherent construction, tends to be bulky.
A third type is a ball valve. The ball valve may offer some advantages of increased flow over the globe valve. The valve actuator connected to the ball is mounted transverse to the flow. As the valve opens, the ball is rotated and aligns a central hole in the ball to the conduit through the valve. The ball valve tends to be somewhat bulky, generally uses two seating surfaces on either side of the ball, and may be somewhat expensive to manufacture.
A fourth type of valve is known as a butterfly valve. The butterfly valve has an internal seat that is typically oriented transverse to the conduit. An external valve stem rotates typically a circular disk transverse to the conduit to engage the seat to block fluid flow. A butterfly valve generally has high flow rates and low maintenance. However, it retains the typical construction of a transverse-mounted valve with a transverse valve stem. While the valve stem may be remotely actuated by motors and other devices known to those in the art, it may not be suitable for sealed installations where it might be desirable to completely encase the valve, remote actuator, and seat in a conduit for efficient installation nor is it suitable for installing in a wall structure where access to the actuator is restricted because of the transverse orientation.
An underlying quest in the various designs of valves is a balance between low friction losses, high flow rates, and throttling characteristics. Other considerations may include freeze resistance, simplicity of construction, cost of manufacturing, and perhaps other specialized uses. While there have been numerous variations of the valve types such as described above, there remains a need to provide an improved flow, low friction valve. This may be especially useful in applications where a remote actuation along a central axis is desired. Typically, these installations involve freeze resistant installations.
In addressing freeze prevention or reduction, efforts have been concentrated on a remote location of a plug of a globe valve away from ambient conditions that could lead to freezing. A typical example is seen in FIG. 7 of U.S. Pat. No. 4,532,954. By remotely locating the plug, the flow of the liquid, typically water, could be stopped a distance in a pipe or a conduit away from the freezing ambient conditions. Those in the art typically concentrated on a globe valve type seat because of the inherent difficulty of actuating a gate valve from within the conduit. In this construction, the nose portion engages a valve seat to seal any flow at a remote location from adverse ambient conditions. As is shown in that figure, the nose must engage a valve seat through the aperture that restricts the flow of water. This remote location results in a beneficial blocking of the water away from the freezing ambient conditions. However, it causes other problems. The wear surfaces may be prone to water erosion and deposits from water impurities. Also, in order to obtain a proper seal, the mechanical advantage of the screw of the valve stem may, after much use, crush the tip of the nose portion. Once the nose was crushed or deformed, it required even harder tightening of the nose which eventually lead to leaking (the famous "drip drip"). Also, the inherent design of the nose portion, engaging an aperture, causes a significant pressure drop, as those with ordinary skill in the art would immediately recognize. This significant pressure drop reduces flow rates. Reduced flow rates may cause a necessarily proportional increase in the size of conduit, valve, or other devices to obtain the needed flow rates. Additionally, the use of the nose section was a modification of the globe valve type seat which required many turns to suitably seal the flow. Likewise, the valve control rod (stem) moved in the typical longitudinal direction--it was not fixed with respect to the conduit or pipe in which it was assembled. Therefore, increased wear and increased maintenance resulted from not only the rotational movement, but the longitudinal movement as it engaged those portions of the valve seat. While an increase in size of the typical valve might achieve the necessary flow rates, typically, this was not a viable option because of size, costs, and compatibility with other components of the piping system.
Thus, prior attempts to remotely seal the water flow or other liquids lead to high pressure drops, low flow rates, and maintenance. The flow rate is especially important in designing sprinkling systems. Both residential and commercial sprinkler systems require a higher flow rate than the typical gate valve or globe valve delivers for given typical size. Thus, an installation was not able to use the typical valving of a typical freeze resistant hydrant--instead, it required a direct connection to other piping with sophisticated valving controls. The sophisticated valving, as those with knowledge of sprinkler systems would recognize, required expensive controls, maintenance, purging during off-season uses, local and national codes, and other issues.
A further complication resulted from the axially rotated valves such as the valves referenced above and others such as U.S. Pat. No. 3,848,806 to Samuelsen, et al. This actuation shows that the valve stem on such axially-rotated valves has been heretofore in the flow path. Until the present invention, on such axially-rotated valves, it may have been considered by those in the art that the valve stem was required to be placed in the flow path in order to engage remotely the nose portion to the aperture. However, the additional turbulence and volume contained by the valve stem in the flow path results in additional loss of efficiency, increased resistance and friction, and lower flow rates.
Thus, as systems have become more sophisticated, a need exists for a valve that can be remotely actuated through the internal structure of a valve away from adverse ambient conditions, and yet be inexpensive, easily installed, of the same or similar diameter to existing piping systems, and still maintain high flow rates and low pressure drops. If a system was available that would allow a high flow rate water hydrant that could be converted to a combination system and water hydrant, it would have an advantage in the market. It would be advantageous to the dwelling owner in a reduction of cost, and it would be advantageous to the builder or installer to simply meet the building requirements of installing outside faucets and yet allow conversion to sprinkler systems at minimal costs.
A significant improvement over the typical valves was attained in the U.S. application Ser. No. 08/637,203, now issued as U.S. Pat. No. 5,718,257 to Robert K. Burgess and upon which this patent claims a priority date. In that patent, it was realized that a fixed longitudinal position with axial rotation could establish high flows and less pressure drop and friction loss and perhaps less maintenance and less costly installations because of its compactness. In that patent, the invention provided a specially designed valve that had a rotatable sealing element longitudinally fixed in position in a conduit which engaged a seating element likewise longitudinally fixed in position in the conduit. The position could be located a sufficient length or distance from for instance, adverse ambient conditions to enable a sealing of flow away from the adverse conditions. That valve significantly improved the flow rates compared to the state of the art known at that time. Test results suggest that the globe valve might have up to approximately 2 times the pressure loss for a given flow rate than the Burgess invention. Similarly, the Burgess invention appears to have about five times less friction loss than the design shown in the '954 reference above. This invention also allowed a quarter turn from a fully-opened to a fully-closed position. Because of its increased flow, it was felt that it would provide a valve of suitable flow rates that could be installed in the same size as a typical conduit and yet meet even the more demanding sprinkler systems requirements. Among other things, however, that valve retained the typical valve stem located in the flow path.
As an example of the significant improvement in pressure drop by the present invention, FIG. 1a shows the pressure drop as a function of flow rate for various commercially available axially-rotated freeze resistant valves. FIG. 1b shows a graph of measured loss coefficients as a function of Reynolds number for the present invention compared to some commercially available axially-rotated valves and other types of valves, again to show some of the significant improvements of the present invention. The two top curves show valves by competitors, such as are designed for higher flow rates on sprinkler feed systems. Although the '203 valve appeared to have significant improvement over technology existing at the time, the present invention shows an even greater flow rate for a given pressure drop or conversely a lower pressure drop at a given flow rate. The present invention may have a 4 times improvement over some of the competition when based on pressure drops at a given flow rate.
Another reference, U.S. Pat. No. 286,508 to Vadersen, et al., shows an early attempt in providing an axially-rotated freeze resistant valve. For some reason, the embodiment apparently was not received commercially. Perhaps, two reasons exist. First, the valve plate (G) with apertures (H), when aligned with valve (K) in apertures (T), as those with ordinary skill in the art would readily recognize, would create nonlaminar flow, increased friction loss, flow separation, and perhaps cavitation (depending on the vapor pressure of the fluid at that temperature). Secondly, the valve stem appears located in the flow path. This is in direct contrast to the present invention which in some embodiments uses an axially-rotated split venturi to avoid the problems of the Vadersen reference. Thus, it may be that from the Vadersen reference to the present invention of 114 years, little improvements along this particular line appear to have been thought appropriate.
The present invention goes beyond the inventions of the earlier valves and even the U.S. application Ser. No. 08/637,203, now U.S. Pat. No. 5,718,257. The present invention improves the flow rates for a given supply pressure several times over the '203 invention. It has a loss coefficient lower than any known axially rotated valve. Its loss coefficient has been tested and may be approximately 50% of a typical axially rotated valve. It may be even simpler to construct, typically avoids the valve stem in the flow path, offers good throttling characteristics, and yet retains higher flow rates for given pressure drops.
Thus, there has been a long felt, but unsatisfied need for the invention that would meet and solve the problems discussed above. The present invention represents the next step in the quest for low friction, high flow and good throttling characteristics, especially in applications where remote actuation of axially-rotated valves is desired. While implementing elements have all been available, the direction of the inventions of other persons have been away from the present invention. The efforts have primarily concentrated on longitudinally moving backward or forward a nose or other sealing element against a valve seat, typically including an aperture. This has resulted in the above-discussed problems, such as poor flow rates. Those in the art appreciated that a problem existed and attempted to solve the problem with technology as shown in U.S. Pat. No. 4,532,954. Even with the improvements of the invention of U.S. Ser. No. '203, the problem still existed at less than optimal flow rates for given pressure drops. Alternatively, those in the art simply accepted the extra expense of extra installations, complicated valving, and other requirements necessary for such applications as sprinkler systems. This general mind set taught away from the technical direction that the present invention addresses. It might be unexpected that a valve can have significantly higher flow rates and yet remotely control or block the fluid flow with the same or similar size conduit or pipe found in a typical installation and still offer an economical solution. Until the present invention, it appears that those skilled in the art had not contemplated the solution offered by the present invention.